Spark plug and ignition lead wire protective system



Aug. 17, 1954 J. B. PLATNER SPARK PLUG AND IGNITION LEAD WIRE PROTECTIVE SYSTEM 2 SheetsSheet 1 Filed Dec. 20, 1951 JNVENTOR. i1 JL? i s W Aug. 17, 1954 J. B. PLATNER 2,536,511

SPARK PLUG AND IGNITION LEAD WIRE PROTECTIVE SYSTEM Filed Dec. 20, 1951 2 Sheets-Sheet 2 g Q """1 Q I .v I Q I Q I I Q w I I I I i I b I v a; N 3 j: w I I L g I m V I I I "I N I 'I -rI Q LI I INVENTOR. J61}?! F/dfrmfr.

fla/ q w Patented Aug. 17, 1954 UNITED STATES hTENT OFFICE SPARK PLUG AND IGNITION LEAD WIRE l PROTECTIVE SYSTEM John B. Platner, Detroit, Mich, assignor to Chrysler Corporation, Highland Park, Mich., a corporation of Delaware Application December 20, 1951, Serial No. 262,628

12 Claims.

This invention relates to protective or shielding systems for protecting the spark plugs and connecting ignition wires or leads of internal combustion engines from oil, dust, moisture, and gases, and more particularly to a combination spark plug and ignition lead protective housing structure for V-type overhead valve engines requiring submerged spark plugs.

Various devices have been suggested to protect the exterior portions of installed spark plugs and their immediate ignition wire connectors from moisture, dust, and oil. These have generally taken the form of plastic or flexible jackets confined to the spark plugs and the immediate wire connectors. They have not been entirely successful as protective media since the lead wires constitute conducting paths for water and/or oil to the plugs within the shield and oil-laden gases emanating from the interior structure of the spark plugs or the mounting openings therefor have often caused the shields and connecting leads to be blown oii the plugs. Moreover, shields f this character have been difiicult to handle especially where the spark plug was necessarily mounted in a well formed in the cylinder head of the engine.

The present invention provides a composite structure believed to better protect the plugs and lead wires of the ignition system.

An object of my invention is to provide a protective system for spark plugs and ignition lead wires of engines of the above type wherein these parts are protected from the oil carried by vapors emanating from the valve mechanism compartments oi the engine.

Another object is to provide a protective system as aforesaid wherein the spark plugs and ignition leads are sealed from external splash water.

A further object is to provide a protective system as aforesaid, wherein the spark plug and ignition lead compartments are ventilated so that blow-by gases from the combustion chamber leaking through the spark plug interior or through the spark plug mounting joint or emanating from the valve mechanism compartment may get out to the atmosphere and wherein the ventilation provided in the system avoids any build up of condensation from blowby gases from these sources.

Another object is to provide a protective systern as aforesaid which inhibits the condensation of external water vapor within the system especially during periods of high humidity and low temperatures and wherein the ignition lead wires emanate from the protective covering at a loca- 2 tion permitting external water drainage away from the plug side of the leads.

Still another object is to provide a protective system for spark plugs mounted in a well of the engine cylinder head whereby drainage water cannot get into the spark plug well.

These and other objects or" my invention will become apparent from the following description and from the accompanying drawings wherein:

Figure 1 is an end elevational view of the rear or flywheel end of a V-8 engine showing the ignition wire cover of my invention applied to each bank of cylinders and showing the manner of connecting the wires to the distributor mounted on the engine;

Figure 2 is a top plan view of one of the lead wire covers of Figure 1;

Figure 3 is an elevational view partly in section of the structure of my invention, the sectional portion being taken on the line 33 of Figure 2;

Figure 4 is a sectional elevation through the spark plug and lead wire portective structure of my invention taken at 44 of Figure 2; and

Figure 5 is an enlarged fragmentary cross sectional View taken at 55 of Figure 2 showing the manner or" sealing the ignition lead wires where they emanate from the protective structure of my invention.

In the drawings in which like reference numerals designate corresponding parts of the structure of my invention, I have illustrated, as seen in Figure 1, an 8-cylinder V-type overhead valve engine of current manufacture to which my invention has been applied.

The engine, as seen in Figure 1, has right and left cylinder banks It) and i2 respectively. The cylinder banks are arranged in a V relationship, each having a cylinder head 14, the valve operating mechanism for which is enclosed beneath a cover H3 secured to the cylinder head, as seen in Figures 1, 2, and 3 by bolts It.

Each cylinder head has a plurality of spaced cylinders it each provided with a combustion chamber 23 above which is a liquid cooling space 2i defined, among others, by the chamber wall 22 and a top wall 24.

Connecting the wal 22 and 24 on approximately one axis of the cylinders are walls 26 of annular formation which define pockets, wells or depressions 23 for receiving and substantially sub-merging spark plugs 30 of conventional character. The spark plug 30 is mounted upon a seat 32 by a threaded base portion 34 which is threadedly received in a threaded bore 35 at the bottom of the well which extends into the chamber 28 to permit the electrode 38 of the spark plug to be dessert 3 exposed to the fuel-air mixture in the chamber 29. A suitable washer or gasket 39 is provided between the spark plug and the seat 32.

Each depression 28 has a machined bore it concentric with the axis of the spark plug in which is securely pressed a cylindrical, rigid, spark plug shield or tube 22 of suitable heat-resisting and shape-retaining material, preferably steel, which surrounds the spark plug and extends vertically above the top wall G3 of the cylinder head cover it as seen at (i l in Figure 4, the said tube forming with an annular metallic ring or tubular member iii a fluid seal or trap generally designated by the numeral 3. The tube 42 is of sufficient size such that the spark plugs may easily be removed and replaced by a suitable wrench provided with a cupped extension having a plug gripping device. The upper end of the tube at A l is, moreover, preferably rounded to remove all sharp corners therefrom.

The ring 45 of the seal t8 comprises a downwardly and inwardly tapered or funnel-shaped wall 5% having inner and outer tapered annular faces 52 and 5%, respectively. The wall 50 may be formed integral with the Wall 43 of the cover E5 and if separately formed includes an annular flange portion 56 intermediate the ends of the ring providing a lip or shouldered portion 58 at the upper end of the ring which is preferably received and tightly fitted in an aperture s of the wall 13 of the cover it and secured to the wall as by soldering or spot welding.

The lower end of the annular wall 59 has a tapered lip portion 52 formed by an annular face 65 which intersects the annular face 52 in a sharp corner 65 and the annular face 54 in a sharp corner 58. The annular corner $6 is closely related to the tube 62 forming an annular air gap of several thousandths of an inch which permits the passage of air but resists the passage of oil therewith from the valve mechanism space under the cover it into the ignition lead wire compartment. Any oil carried by vapor to the seal id will collect on the lip 62 from which it will drip oil into the valve mechanism compa-rtment.

As seen in Figure 4, the insulated ignition lead is is provided with a spring contact clip 52 which snaps over the terminal end M of the spark plug 3d and is protected from flashover by a suitable tubular shield '16 forming no part of this invention which may be of ceramic or other suitable insulating material, and comprises an elongated tubular portion 13 embracing the lead Wire 79 and extending to a point adjacent the upper end of the spark plug tube 42 and which has a lower outwardly flaring lip or portion 3% Which eX- tends over the terminal connection and over a portion of the insulating wall of the spark plug.

The lead wires it from the individual spark plugs are turned down as they emanate from the shield "56, and are arranged as seen in Figures 2 and 3, to extend longitudinally of the cylinder head cover it in the direction of the rearward end or" the engine where they connect with the distributor generally designated by the numeral E2.

Protecting the ignition lead wires l9 and the spark plug chambers from external Water, dirt, etc, is a rigid metal housing generally designated by the numeral 35 which comprises a rectangular frame portion 68 formed, as seen in Figures 2, 3, and 4, by side walls 96 and 92 and end walls 9%, 96 and a cover 98. The frame 88 is suitably mounted on the wall it of the valve mechanism cover It as by welding, and the cover 98 is secured to the upper face of the frame through an intervening gasket we to provide an air-andwater-tight joint therewith, the cover being held in position by countersunk head screws 582 which are received in depressed lip portions ii i of the cover t8 and are threaded into suitable shouldered posts id of which three are illustrated, the latter being suitably held as by riveting, soldering, or spot welding to the cylinder head cover it. Suitable copper or other type sealing washers 1533 are provided under the heads of the screws Hi2,

The'housing 86 is relatively shallow in character and is of a width and length sufficient to extend over the spark plug tubes #32 and provide adequate space to neatly confine the ignition wire leads without causing damage to them. A width slightly greater than the diameter of the posts 5636 plus four lead wire diameters will generally sufiice for an 8-cylinder engine, there being four wires confined in each of the two housings provided on such an engine as is disclosed in Figure 1.

The wall 92 of the housing frame 35, which is at the inner side of the cylinder bank E6 of the engine, is provided adjacent the wall El i thereof at the rearward end of the cylinder bank it with four apertures Iii? which receive, as seen in Figures 2, 3, and 5, suitable plastic insulating bushings or tubes H2 which are provided with a recess 6 id intermediate their length for interfitting with the peripheral portion of the apertures Hi1. By preference, these bushings Will be made of a synthetic resin or a rubber-lire material like neoprene. The bushings i 82 have central apetures 555 through which the lead wires it may be drawn and which are tightly gripped by the bushing to provide awater and vapor seal therewith.

Suitable clips or tubular confining members may be provided at the posts 93 or at other points between the adjacent spark plug tubes to hold the adjacent lead wires together in a compact group such that the lead wires will stay in position after the cover 98 is removed and, moreover, to avoid sharp bends in the lead wires. These clips or tubular members may be of suitable heat-resistant insulating material and if made of metal are preferably coated and have all edges rounded. If desired, the inner surface of the housing 88 may be coated with a suitable insulating and/or rust-resisting material such as a phenolic resin coating.

Since the housing 86 and the lead wires 19 are completely sealed in with respect to the cover any ventilation obtained within the housing and spark plug chamber is necessarily derived from the normal breathing and ventilation or the engine by way of the valve mechanism compartment beneath the cover it. For best results, however, some additional ventilation has been found to be desirable for clearing the air in the housing 86 and spark plug chamber contaminated by blow-by gases from the valve mechanism compartment or emanating from within the spark plug structure or leaking through the threaded joint 34 of the spark plug with the combustion chamber 2&3. In such instances I preferably provide one or more vents 22 in the cover 923, these vents being formed by an aperture I22 which is covered by a suitable wire screen 12 held in place by a bezel I26 having an aperture I28 formed with a tapered lip its. Exterior of the cover 93 immediately over the aperture 22,

is a cover piece or water shield I32 formed by a sloping wall I34 having a conical surface and the side edges i36, 138 of which abut the cover 98. A flat extension Hi6 provides a means for securing the shield. H32 and the screen and bezel to the cover 98 as by riveting. It will be observed that the wall 134 of the shield H32 flares outwardly a direction away from the cover 58 and. away from the forward end of the engine. This is by preference since the air currents from the fan at the forward end of the engine in passing over the edge of the shield K52 produce a suction effect at the aperture E22 to aid ventilation of the housing 85 and the spark plug oompartment. The lip 30 of the bezel serves as an oil drip edge.

Between the apertures H5 of the lead wire bushings H2 in the housing 86 and the distributor 82, the ignition lead wires may be clamped at one or more places against the cylinder head cover IS by suitable straps 150, shown in Figure 1, which are secured by bolts N32 to the cylinder head M.

It will be evident that by providing a further metallic enclosure for the exposed portions of the lead wires in Figure 1, a fully shielded enclosed ignition system to prevent radio interference from the ignition and other sources may be secured.

It will be observed that the ignition lead wire outlets I are at the rearward end of the engine which end is generally lower than the front end of the engine when the latter is mounted on the vehicle chassis. Hence any splash water can readily run or drain off away from the housing 86 and the lead wires 19. Moreover, it has been previously noted that the spark plug tubes 42 project upwardly at M in Figure 4 above the cylinder head cover i3. Hence should for any reason water get under the housing 86, it cannot get into the spark plug compartment 22 and would drain toward the rearward end of the engine.

It will also be noted that any vapor emanating from the internal structure of the spark plugs 3% or through the threaded connection 33 between the spark plug well 28 and the combustion chamber 28 can find escape through the liquid seal 48 into the rocker arm compartment by way of the normal engine ventilation and preferably by way of the ventilator E26 provided in the cover S8 of the housing 88 through which fresh air can enter the system to ventilate the spark plug compartments and the lead wire housing. The described structure, moreover, is of a character wherein it has been observed in actual use that practically no condensation forms on the under side of the housing 86, even under conditions providing low ambient temperatures with high humidity.

Although it will be apparent that the illustrated embodiments of my invention are well calculated to adequately fulfill the objects and advantages of my invention described above, it will be understood that my invention is susceptible of variations, modifications and changes within the spirit and scope of the appended claims.

I claim:

1. In an internal combustion engine having a cylinder head, a spark plug on said head, overhead valve mechanism carried by said head and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising a tubular member surrounding said plug and having one end secured in said head and the other end extending through the top of said valve mechanism cover, tubular means carried by said valve mechanism cover and including a portion in close relationship to but forming a peripheral air gap with said member for providing a liquid oil trap between said member and said valve mechanism cover and a sealed ignition lead housing straddling said member and carried by said valve mechanism cover.

2. In an internal combustion engine having a cylinder head, a spark plug on said head, overhead valve mechanism carried by said head, and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member entirely open at both ends, having one of its ends telescopically sealed in said head and its other end extending through the top of said valve mechanism cover, tubular means carried by said valve mechanism cover and including a portion in close relationship to but forming a peripheral air gap with said member for forming a liquid oil trap between said member and said Valve mechanism cover adjacent said other end of said member, and an ignition lead enclosure straddling said member and carried by said valve mechanism cover, said enclosure being sealed against infiltration of liquid and gases from outside said enclosure.

3. In an internal combustion engine having a cylinder head, a spark plug in a well in said head, overhead valve mechanism carried by said head, and a dished cover enclosing said valve mechanism and siad Well; a protective structure for said spark plug and the ignition lead therefor comprising an elongated substantially rigid tubular member surrounding said plug and open at both its ends, one end of said member tightly interfitting with said well and the other projecting outwardly from said Well through said valve mechanism cover, tubular means carried by said valve mechanism cover and including a portion in close relationship to but forming a peripheral air gap with said member for providing a fluid oil trap between said member and valve mechanism cover adjacent said other end of said member, and an ignition lead enclosure straddling said member, said enclosure comprising a continuous outer wall rising from said valve mechanism cover and integral with this cover, a cover plate secured to said wall and a sealing gasket between said plate and Wall.

i. A protective structure as claimed in claim 3 wherein said wall has a lead wire aperture therein from which said lead wire may extend and means providing a seal between said lead wire and said aperture.

5. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head, overhead valve mechanism carried by said head, and a dished cover enclosing said valve mechanism and said well; a protective structure for said spark plug and the ignition lead therefor comprising an elongated tubular member surrounding said plug and having one end secured in said well, and the other end extending through the top of said valve mecha nism cover, a liquid trap member carried by said valve mechanism cover, including an annular extension surrounding said member and projecting downwardly from the top of said valve mechanism cover, said extension having an internal inwardly tapering annular surface terminating just short of intersection with said member whereby to provide close clearance therewith, an external annular surface, and a tapered lip provided by an annular end surface beginning at the said point of termination of said internal surface and extending downwardly and outwardly to intersect said external surface in a substantially sharp edge, and a sealed lead wire enclosure straddling said member and carried by said valve mechanism cover.

6. In a liquid oil trap for an internal combustion engine spark plug and ignition lead wire protective structure, a cylindrical member, an annular cylindrical element surrounding said member and having a wall tapering inwardly toward said member, said wall having an internal edge in close proximity to the external cylindrical surface of said member and having a tapered drip lip extending outwardly and away from said surface commencing at said internal edge.

7. In an internal combustion engine having a cylinder head, a spark plug relatively submerged in a well in said head. overhead valve mechanism carried by said head, a d hed cover enclosing said valve mechanism and said well, and a fan for directing an air cu rent longitudinally of the engine from front to rear thereof over said cover; a protective structure for said spark plug the ignition lead therefor comprising a tubular member surrounding said plug, one end of said member being secured in said well, and the other end extending through the top of said valve mechanism cover, means providing a liquid oil trap between said member and said valve mechanism cover, a water-tight housing straddling said member carried by said valve mech anism cover and a vent structure on said housing, said vent structure having a shielded outlet subject to the downstream effect of said air current.

8. A protective structure as claimed in claim 7 wherein said vent structure is located in the cover plate of said housing.

9. A protective structure as claimed in claim 7 wherein said vent structure comprises an aperture in said housing, a screen over said aperture, a bezel ring and a hood over said aperture, said hood opening on the downstream side of said air current.

10. In an internal combustion engine having a pair of cylinder ban s forming a V with each other, said banks being pitched downwardly longitudinally from the fan end of the engine when the latter is assembled in a vehicle, a plurality of longitudinally spaced cylinders in each bank, a plurality of spark plugs relatively submerged in wells in said heads, one being positioned over each cylinder, and a dished cover secured to each h ad and covering the valve mechanism or" that head; a protective structure for said spark plugs and the ignition lead wires thereof comprising an elongated cylindrical member surrounding each spark plug and mounted in each well, said member having one of its ends secured in the well in which it is mounted and having its other end projecting through the top wall of said valve mechanism cover, means providing a liquid oil trap between each said member and said valve mechanism cover at a position within this cover, a detachable ignition lead wire connected to each said spark plug and extending over the membe in which it is connected, said lead wires being arranged to extend toward the low end of the cylinder bank in which they are connected, an elongated generally rectangular ignition lead housing straddling said members and lead wires and comprising a substantially rectangular shaped upstanding wall extending longitudinally of the engine and integral with said valve mechanism cover, said wall retain ng said lead wires in their prearranged paths, an outlet aperture for each lead wire in one longitudinal portion of said wall at the low end of the bani; and on the inner side thereof, a plastic grommet surrounding each lead wire and sealing the same relative to its outlet aperture, a cover plate seated on said wall and secured thereto by fastening means operating between this cover plate and said valve mechanism cover and sealing means between said cover plate and wall and between each iastening means and said cover plate.

11. A protective structure as claimed in claim 10 including ventilation means on said cover provided with a hood opening on the downst' earn side of the air current delivered by fan.

12. in an internal combustion engine having a cylinder head, a snail; plug mounted on said head, valve mechanism carted by said head, and a cover over said valve mechanism and plug; a protective structure for plug the ignition lead therefor compri ing an elongated tubular member surrounding said plug and having one end thereof projecting through an open ing in said cover, a liquid trap member carried by said valve mechanism cover, including an annular extension surrounding said projecting downwardly from the top oi said valve mechanis cover, said extension having an ternal in dly tapering annular surface terminating just short of intersection with said incinber whereby to provide, close clearance therewith, an external annular surface, and a tapered lip provided by an annular end surface beginning at the said point of termination of said internal surface and extending downwards; and outwardly to intersect said ex, rnal surface in a substantially sharp edge.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,499,594 Riley July l, 19% 1,933,423 Forsyth Oct. 81, 1933 2,625,146 Stephel Jan'lZ, 1953 FQREIGN PATENTS Number Country Date 556,790 Great Britain Oct. 21, 1943 977,954 France Nov. 22, 1950 

